1. Field of the Invention
The present invention relates to a system and method for correcting pattern data of an integrated circuit or the like so as to cancel the light proximity effects. The present invention also relates to a method of forming a pattern using such a method for correcting the light proximity effects.
2. Description of the Related Art
Referring to FIGS. 29A to 29D, a conventional LSI production process will be described below. First, an LSI pattern such as that shown in FIG. 29A is designed using a CAD system or a similar tool and corresponding LSI pattern data is produced. The designed LSI pattern includes a plurality of rectangular patterns 291. Electron beam exposure is then performed according to the designed pattern data so as to produce a mask including a plurality of patterns 292 as shown in FIG. 29B. A wafer is exposed to ultraviolet light through the mask thereby transferring the pattern 292 formed on the mask onto the wafer. However, the pattern transferred to the wafer becomes different from the mask pattern consisting of rectangular patterns 292 owing to diffraction of light in that corners of rectangles are rounded as shown in FIG. 29C. If the wafer is etched or subjected to a similar process using the transferred pattern 293, then the resultant pattern 294 formed on the wafer has further deformation due to the micro coding effect as shown in FIG. 29D. If the wafer is then subjected to an oxidation process to form a local oxidation of silicon (LOCOS); isolation structure, the pattern is deformed further owing to the so-called bird""s beak effect.
In production of an integrated circuit such as an LSI, the pattern deformation accumulates via a series of various production processes as described above, and the actual size of the pattern obtained at the end of the production processes is generally different from the designed size.
In recent years, with the reduction in the size of patterns of integrated circuits, it is required to control the pattern size more precisely. In practice, however, there occurs pattern deformation such as that described above during production processes, and electrical characteristics of devices and various margins are influenced by the pattern deformation to a degree that cannot be neglected.
It is a general object of the present invention to solve the problems described above. More specifically, it is an object of the present invention to provide a light proximity effect correction apparatus and method for alleviating the deformation of patterns due to light proximity effects~ during production processes of an integrated circuit.
It is another object of the present invention to provide a method of forming a pattern according to such a method of correcting for light proximity effects.
According to a first aspect of the present invention, there is provided a light proximity correction system including: a design data input unit for inputting design data of a circuit pattern; a data compression unit for compressing the design data input via the design data input unit; an optical image formation unit for forming an optical projection image used to transfer a pattern onto a wafer according to the design data input via the design data input unit; a prediction unit for predicting the size of the pattern which will be transferred onto the wafer, the prediction being performed on the basis of the projection image formed by the optical image formation unit; a comparison unit for calculating the difference between the size of the transferred pattern predicted by the prediction unit and the size of the pattern designated by the design data input via the design data input unit; a correction unit for correcting the design data compressed by the data compression unit by an amount equal to the difference determined by the comparison unit; a data expansion unit for expanding the data corrected by the correction unit; and a corrected data output unit for outputting the data expanded by the data expansion unit.
According to a second aspect of the present invention, there is provided a light proximity correction method, including the steps of: compressing design data of a circuit pattern; forming an optical projection image used to transfer a pattern onto a wafer according to the design data; predicting the size of the pattern which will be transferred onto the wafer, the prediction being performed on the basis of the projection image formed in the previous step; correcting the design data by an amount equal to the difference between the predicted size of the transferred pattern and the size of the pattern designated by the design data; expanding the corrected data; and outputting the expanded data.
According to a third aspect of the present invention, there is provided a method of forming a pattern, including the steps of: correcting the light proximity effect which occurs during a process of transferring a pattern onto a wafer, the correction of the light proximity effect being performed on the basis of design data of a circuit pattern, thereby generating corrected data; performing electron beam exposure according to the corrected data thereby producing a mask pattern; performing light exposure through the mask pattern thereby transferring the mask pattern onto a wafer; and processing the wafer using the transferred mask pattern.